JP2620502B2 - Electrical interconnects and assemblies with helical contacts - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

FIELD OF THE INVENTION The present invention relates to electrical interconnects, and more particularly, to a number of connections between each pair of conductors located on or within each pair of electrical circuits, such as a printed circuit board or module. Are provided at the same time.

[0002]

BACKGROUND OF THE INVENTION Cross Reference of Applications Under Examination: F. U.S. Pat. No. 5,299,939 "Spr by Walker et al.
"ing Array Connector" (filed March 5, 1992) shows a spring array connector including a resilient spring core, wherein an electrically insulating layer is disposed parallel to the core, and an electrically conductive segment is formed of the insulating layer. A plurality of electrical contacts are electrically connected to the conductive segments, located at the upper location, each of the plurality of springs in the array being independently bendable, in embodiments, sheet and wire sine, spiral. , Cantilevered and buckled beam shaped springs are shown.

[0003] As shown herein, the present invention is particularly applicable to the field of information processing systems (computers) where high density connections are standard. In such use, the interconnects formed must meet high standards for reliability. Further, it is often desired that such connectors be separable and reconnectable in the field within the final product to ensure effective repair and replacement, eg, for upgrades and the like. Such separability is also required in the assembly of various products that use these connectors to facilitate product testing. In addition, the final structure of such interconnects must be tolerant of dust and other debris that can accumulate during the life of the connection. 2 between printed circuit board and module
When interconnecting two circuit members, there may be non-planarities of the conductor surface (and the structure containing such conductors), which assures an effective and reliable connection between the members. Must be corrected in order to do so.

[0004] Known methods of providing various interconnects include:
There is wire bond technology. This mechanically and thermally connects a soft metal wire, such as gold, from one circuit to another. However, such bonding does not facilitate high density connections due to the possibility of wire breakage and the mechanical difficulties in handling the wires. To another technology,
There is a method in which solder balls and the like are arranged between respective circuit elements such as pads, and the solder is reflowed so as to be effectively interconnected. Although this technique has been very successful in providing high density interconnects in various structures, it does not allow for easy disconnection and subsequent reconnection. Yet another technique uses an elastomer that includes multiple conductive paths, such as by small diameter wires or columns of conductive material, to provide the interconnect. Known techniques using such elastomeric materials typically have the following disadvantages. (1) A strong force is usually required per contact. (2) The electrical resistance through the interconnection between related circuit elements such as pads is relatively high. (3) Sensitive to dust, debris and other environmental factors that adversely affect a sound connection. (4) The density is limited due to physical limitations of a specific connector design or the like.

[0005] Various techniques for providing electrical interconnection to various electrical circuit members are disclosed in US Pat.
No. 732, No. 3960424, No. 4161346
Nos. 4,655,519, 4,295,700, 4,664,458, 4,688,864, and 4,971,565. Reading these patents, these techniques include, besides the many disadvantages mentioned above, such as potential misalignment, and low density, as well as other disadvantages, such as relatively complex designs, expensive manufacturing costs, etc. It is understood that.

It is believed that high density electrical interconnects that can provide effective and reliable connections provide significant benefits. (Such connections are repeatable to facilitate connection and reconnection, and provide other useful mechanisms that will be understood from the description below.)

[0007]

Accordingly, a primary object of the present invention is to improve the technology of electrical interconnects.

It is another object of the present invention to provide an electrical interconnect that provides a high density of interconnects that can be easily separated and repeated when needed and has improved characteristics of high reliability. It is to be.

Another object of the present invention is to provide an interconnect with a relatively simple design, which is less expensive to manufacture.

[0010] Yet another object of the present invention is to provide an electrical assembly that uses the interconnects shown herein.

[0011]

According to a first aspect of the present invention, there is shown an interconnect for electrically interconnecting an electrical conductor on one circuit member to an electrical conductor on a second circuit member. It is. The interconnect includes an insulating sheet disposed between both circuit members and at least one electrically conductive element. The electrically conductive element includes a relatively flat base portion on or within the insulating sheet, and a helical portion extending away from the flat base portion and the insulating sheet. This helical portion is adapted to be connected to one of the electrical conductors of a circuit member.

In accordance with a second aspect of the present invention, there is provided an electrical assembly including first and second circuit members and an interconnect for electrically interconnecting conductors on said members. This interconnect has the mechanism described above.

According to a third aspect of the present invention, there is provided an information processing system including the above-described electrical assembly.

[0014]

Referring to FIG. 6, there is shown an electrical interconnect 15 according to an embodiment of the present invention. Interconnector 15
Is specifically designed herein to electrically interconnect the first and second electrical circuit members, providing a high density interconnection between such circuit members as is strongly desired in the computer industry. provide. Examples of suitable circuit members interconnected according to the present invention include printed circuit boards, electronic circuit modules, and the like. It is well known to use such boards, modules, etc. as part of a processor cage structure in a computer. As used herein, the term "printed circuit board" is meant to include a multilayer circuit structure that includes one or more conductive layers (eg, signal, power, and ground). Such printed circuit boards are often referred to as "printed wiring boards". As used herein, the term "circuit module" includes a substrate or similar members having various electrical components (eg, semiconductor chips, conductive circuits, conductive pins, and the like) that are components thereof. Means that Examples of such modules are
These are described in U.S. Pat. Nos. 4,688,151 and 4,912,772 and are shown in FIG. 7 (described below). No further explanation of these modules is deemed necessary and will be omitted here.

The interconnect 15 has several advantageous features, as shown herein. In particular, the present invention provides for each conductor of a circuit member to be connected,
It is possible to provide a uniform contact force. The present invention is also adaptable to high speed electrical structures by ensuring a minimum inductance and a minimum capacitance between adjacent conductive elements (when a large arrangement of such elements is used). Thus, the interconnect of the present invention guarantees essentially minimal signal degradation in many computer systems. Further, the interconnects of the present invention can be produced at relatively low cost and operate in a relatively simple manner. Further, the interconnects shown herein can easily overcome non-planarities between adjacent circuit members or between conductors thereon, and the effect between such members under all operating conditions. Secure connection. As further shown, one embodiment of the present invention provides for an effective connection to each conductor by removing debris or other materials that may impair such connections.

As shown in FIG.
Includes an insulating sheet 17 disposed between the first and second electrical circuit members 19 and 21 (FIG. 7). In FIG. 7, the member 19 is represented as a module and its lower surface 2
7 includes a substrate 23 having a plurality of conductors 25. Each conductor is preferably a metal pad (for example, copper) having a relatively flat structure, but may be another structure known in the art. It is desirable to overplate conductor (25) with nickel and gold to avoid corrosion and provide a reliable connection in the present invention. Circuit member 1
9 also includes a plurality of semiconductor chips 29 (only one is shown in FIG. 7), which is electrically connected to conductors 25 through internal circuits (not shown) in substrate 23.
An additional cover 31 or the like is provided on the upper surface 33 of the substrate. A typical substrate material corresponding to circuit member 19 is ceramic, but other materials can of course be used.

In FIG. 7, the underlying circuit member 21 is shown as a printed circuit board, which is a known material (eg, reinforced fiberglass epoxy resin).
And includes a substrate portion 35 that contains a plurality of conductive planes (eg, signal, power, or ground) therein as described above. A plurality of electrical conductors 37 are disposed on the top surface of the circuit board and are electrically connected in various internal planes through acceptable means (eg, conductive vias or plated through holes). Conductor 37
(Eg, copper) is similar to conductor 25 and is preferably overplated with nickel and gold for the reasons described above.

6 and 7 show that the insulating sheet 1
7 are arranged in a predetermined arrangement between the circuit members 19 and 21. Such an arrangement is achieved using a plurality of arrangement pins 41 (only one is shown in FIG. 7), with each pin having a respective aperture 4 located in circuit members 21 and 19.
3 and 45. The arrangement of the insulation sheet 17 is achieved by providing an opening 47 in the insulation and passing one of the pins 41 therethrough. In an embodiment of the present invention, a total of two pins 41 are used, each located at a respective diagonal corner of a generally rectangular structure. However, this is not a limitation of the present invention, and additional pins may be used.

In FIG. 6, the insulating sheet 17 includes upper and lower layers 5.
1 and 53 are shown. Each layer is preferably comprised of a polymeric material, such as polyimide, which is laminated on the outer surface of the intermediate electrically conductive element 55 representing the electrically conductive portion of the interconnect 15. Each polyimide layer 51 and 53 is preferably between about 0.001 inch (0.025 mm) to about 0.003 inch (0.025 mm).
75 mm). Although only one such conductive element is shown in FIG. 6, it will be appreciated that several such elements may be used depending on the operational requirements in the final assembly using the present invention. In one example, a total of 625 such elements 55 are used.

The conductive element 55 has a relatively flat base portion 5
9 which is located between the outer surrounding layers 51 and 53, as shown in FIG. Alternatively, the conductor, including the relatively flat base portion 59, may be located outside of a single insulating layer, such as polyimide, and the portion of the present invention may comprise a double layer structure. Included in the scope of. In addition, the conductor element 55 has a flat base portion 59
And at least one elastic helical portion 61 extending away from the helical portion. In the embodiment of FIG. 6, two helical portions are shown, each extending in opposite directions (up and down) from a central portion that is a relatively flat base portion 55.
Each helical portion is designed to connect a respective electrical conductor 25 or 37, as will be appreciated. In the embodiment of FIG. 6, the spiral portion 61 extending upward has the member 19
The spiral portion 61 extending downward is designed to connect the upper conductor 25, while the spiral portion 61 extending downward is designed to connect the conductor 37 on the lower circuit member 21. Thus, the interconnect 15 provides an electrical connection between the first conductor 25 and the associated second conductor 37.

Although two oppositely oriented helix portions 61 are shown in FIG. 6, it will be appreciated that alternative embodiments are also within the scope of the present invention. For example, as shown herein, a single helix may be used to provide another means of connecting to other conductors.
Such an embodiment is shown in FIGS. 9 and 11 and will be described in detail hereinafter. Also, one side of the interconnect
It is also possible to provide two helical parts and to guarantee a double connection. Such a mechanism would be particularly meaningful and desirable.

Referring to FIGS. 1-5, various steps for creating an interconnect 15 according to an embodiment of the present invention are shown.
In FIG. 1, a single sheet 71 of flat conductive material is provided. A preferred conductive material for this sheet that actually forms the conductive elements of the present invention is beryllium copper. Other metallic materials are acceptable and include, for example, phosphor bronze. In one example, about 0.005 inches (0.125 mm)
A thick sheet 71 is used, the size of which is about 1.
5 inches square. A total of 625 conductive elements can be formed in a sheet of this size, indicating that the invention can achieve extremely high densities.

A helical portion 73 and a rectangular "pad" 77 (each associated with an element) of a predetermined shape are formed in FIG. 1, preferably using an etching process or the like. Since such processing is well known, further description is omitted here. Each of the formed curve elements is shown in FIG.
It is to be understood that this constitutes an extending helical portion of each conductive element 55 of the present invention shown in FIG. Further, openings 75 are preferably provided as shown, and the alignment pins 41 are provided.
(FIG. 7). The patterns required to allow etching of the curved elements and pads shown in FIG. 1 are provided by well-known photographic printing processes used in many printed circuit board manufacturing operations. Therefore, the description of this is omitted here.

FIG. 2 shows the spiral portion 73 and the pad 77 to be formed. Each helical portion 73 is formed inside a rectangular pad 77, and each pad 77 is connected to an adjacent pad or peripheral boundary (peripheral) portion 79 of the sheet 71 by a connection tab 8
1 are connected. Each pad 77 is connected on each of its four sides by one of these tabs. In one example of the invention, each tab measures only about 0.005 inches (0.125 inches).
mm) to 0.010 inches (0.25 mm). Although etching has been shown as a preferred means of material removal from sheet 71, other means, such as laser removal and stamping, are within the scope of the invention.

As shown in FIG. 3, the sheet 71 having the same configuration as that of FIG. 2 is covered on both sides with insulating materials 51 and 53 (described above). Preferably, the insulating material is applied using lamination techniques, and several such methods are known and need not be described herein. A window 91 is provided in each layer associated with one element 73. This window is preferably rectangular,
It is slightly smaller than the corresponding width of the rectangular pad portion 77. This slight overlap is shown in the cross-sectional view of FIG. Each layer 51 and 53 has the thickness described above in connection with FIG. Each window 91 is preferably square and has a side dimension of about 0.035 inch (0.875 inch) each.
mm), while pad 77 has a slightly larger dimension of 0.045 inch square (1.14 mm square).
The overall thickness of the structure of FIG. 3 including the two insulating layers and the intermediate metal sheet 71 is about 0.010 inches (0.25 mm). As shown in FIG.
They are arranged in rows. The openings 47 are also provided for the insulating layer as shown, and these are aligned with the respective openings 75 in the sheet 71.

According to an embodiment of the present invention, a plurality of dendritic elements 93 are provided at the end of the curve of the spiral portion 73 in the next manufacturing step of the present invention. In the embodiment of FIG. 4, these elements 93 are only shown at one of the ends of the curve, and project upward in the perspective view. This particular segment, as shown in FIG.
In the case of forming a conductive element projecting in the opposite direction also on the lower side, such a dendritic element is likewise provided for the adjacent curved end portion. Dendritic Element Formation Canadian Patent No. 1
No. 121011, which is also referred to in the present invention. However, this is not a limitation of the present invention, and other techniques adapted to these factors can be used. As noted in this patent, these elements are preferably comprised of a conductive material selected from the group comprising palladium, platinum, rhodium, ruthenium, osmium, iridium, and tungsten. These elements are grown on a metal (beryllium copper) substrate, around which the polyimide insulating material forming layers 51 and 53 is placed. Such growth does not adversely affect the layer. The use of dendritic elements constitutes an important aspect of the present invention in connection with some of the advantages associated with these elements described in the aforementioned patents. For example, such elements are effective in removing debris from each connected surface. As mentioned above, the conductive elements of the present invention can connect flat surfaces (eg, copper pads), and can also connect conductors having dendritic or similar elements as described herein. In either case, the dendritic element 93 provides a secure and effective connection. More importantly, such a connection is achieved in a non-wiping manner due to the shape of the helical portion of the conductive element of the present invention and the compressibility of the connection.
Dendritic element 93 is also shown in FIGS. In one example of the invention, a total of about 1000 dendritic elements 93 are formed at each end of the curve.

In FIG. 5, a rectangular segment 77 is
Boundary (periphery) of adjacent segment and intermediate sheet 71
It is electrically isolated from the portion 79. This is accomplished by punching or laser ablation, and an aperture 95 is formed in the composite structure. Each aperture extends through the entire thickness of the composite structure. This punching or similar removal operation is performed by connecting tab 81
, Thereby isolating previously formed pad portions to form the ultimately identified conductive element 55. This step precedes the helical elongation step, the configuration of which is shown in cross-section in FIG.

In the next step of the invention, the helical portion of the invention is extended outward by a predetermined distance. Such elongation is preferably achieved by a die forming operation,
Each helical portion is formed to the desired dimensions. In an embodiment, each helical portion extends a distance (dimension "D") of about 0.020 inches (0.5 mm) from a respective outer surface of the adjacent insulating layer. However, this is not a limitation of the present invention, and may be extended to other dimensions, depending on the corresponding dimensional limitations of the structure using the present invention.

The above thickness and distance interconnects have a minimum contact pressure of approximately 50 grams from each helix.

Prior to formation of dendritic element 93, it is preferred to plating the outer surface of beryllium copper with a layer of nickel, followed by providing an ultra-thin coating of a noble metal (such as gold). In this case, nickel functions as a diffusion barrier. The indicated dendritic element is then formed (eg, grown) on the metal substrate. In one example of the present invention, about 6
A nickel layer having a thickness of 0 to 80 microns and a gold layer having a thickness of about 50 to 100 microns are formed. These additional plating steps should preferably be performed prior to lamination of the polyimide insulation layer, but will be performed later and the window 9 shown
It is also possible to plate only one, thereby saving material and cost.

FIGS. 8 to 11 show another embodiment of the present invention.

In FIG. 8, the interconnect 15 includes double helical portions 61, each of which extends from the base portion 59 of the conductive element in a single common direction (downward in FIG. 8). Have been. This is achieved simply by pushing down both helical parts shown, for example in the embodiment of FIG. 5, downwards. The advantage of this structure guarantees a double connection with each conductor 37 to be connected. Each end of these helical portions preferably includes the dendritic element 93 described above. FIG. 8 also shows a base portion 59.
There is a means 97 for providing an electrical connection between and the conductor 25 . In the embodiment of FIG. 8, this means preferably comprises a plurality of dendritic elements 9 formed on the opposite side of the base portion 59.
3 ', this dendritic element 93' is formed in a manner similar to element 93. These dendritic elements 9
3 'can be formed simultaneously with element 93.
Dendritic element 93 'attracts circuit members 19 and 21,
Thereby, it is connected to the conductor 25 while compressing the interconnector 15. Such compression of the circuit members is performed using various conventional means (eg, external clamping arrangements), but will not be described here.

In FIG. 9, the interconnect 15 includes a single helical portion 61 projecting downward, and the area where the other helical portion was formed in the previous example is maintained flush with the base portion 59. Dendritic elements 9 in another surface area
3 'is added, which forms an electrical connection with the conductor 25.

As can be seen from FIGS. 8 and 9, in these figures the connection with the respective conductors 25 and 37 has not yet occurred. This is so indicated for the purpose of observing the state of the various parts of the invention before such a connection is made. Upon connection, the helical portion of the present invention is compressed by a predetermined distance, thereby creating an effective connection. In one example of the present invention, each of the helical portions of the present invention has an initial height (dimensions) shown in FIG.
D ") from about 0.020 inch (0.5 mm).

In FIG. 10, the interconnect 15 includes a double helical portion 61 as in FIG. Means 97 preferably includes an amount of solder 99 to provide an electrical connection between interconnect base portion 59 and adjacent conductor 25. In an embodiment of the present invention, the solder 99 has a tin to lead ratio of 63:37. That is, tin accounts for 63% of the solder mix, and lead accounts for the remaining 37%. Other solders can, of course, be used, for example, with a tin to lead ratio of 90:10, ie, tin accounts for 90% and the remaining 1%.
Solder or the like in which lead accounts for 0% can also be used. This provides a fixed type connection between the conductor element of the invention and the respective conductor to be connected.

The embodiment of the present invention shown in FIG. 11 is similar to that of FIG. 9 except for the solder material 99, and is also similar to the embodiment of FIG. This is used to form a relatively fixed connection between the conductor 25 and the conductive element 55. The use of a single helix as shown in the embodiment of FIG. 9 ensures a larger surface area for receiving solder.

[0037]

By designing the interconnect to be located between two circuit members, an electrical interconnect for interconnecting a pair of circuit members is provided. It is important to note that the invention ensures an effective connection between the non-planar respective circuit members or the conductors arranged thereon. As mentioned above, the present invention is simple to generate and relatively easy to operate. Although the invention has been described as a means for providing electrical connection between each pair of conductors, it can also be used as a metal conductor for thermal conduction (eg, thermal conduction between modules).
Thus, the use of the interconnect structure shown herein in combination with a plurality of such heat conducting members ensures both thermal and electrical paths at designated locations within the coupling structure. Becomes possible.

[Brief description of the drawings]

FIG. 1 illustrates various steps of creating an interconnect according to an embodiment of the present invention.

FIG. 2 illustrates various steps of creating an interconnect according to an embodiment of the present invention.

FIG. 3 illustrates various steps of creating an interconnect according to an embodiment of the present invention.

FIG. 4 illustrates various steps of creating an interconnect according to an embodiment of the present invention.

FIG. 5 illustrates various steps of creating an interconnect according to an embodiment of the present invention.

FIG. 6 is an enlarged side view showing a cross section of a part of FIG. 5, showing an embodiment of the interconnector of the present invention.

FIG. 7 illustrates a partial side view of an interconnect of the present invention disposed between a pair of electrical circuit members and providing electrical connection between respective pairs of electrical conductors.

FIG. 8 is an enlarged side view of a portion of FIG. 7 showing various interconnect embodiments of the present invention.

FIG. 9 is an enlarged side view of a portion of FIG. 7 showing various interconnect embodiments of the present invention.

FIG. 10 illustrates various interconnect embodiments of the present invention.
It is the side view which expanded and showed the one part cross section of FIG.

FIG. 11 illustrates various interconnect embodiments of the present invention.
It is the side view which expanded and showed the one part cross section of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 15 Interconnector 17 Insulation sheet 19, 21 Electric circuit member 29 Semiconductor chip 35 Substrate part 37 Electric conductor 41 Arrangement pin 43, 45, 95 Aperture 47, 75 Opening 55 Intermediate electric conductive element 59 Base part 61 Spiral part 81 Connection tag 91 Window 93 Dendritic element 99 Solder material

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Fresa Patrick Donlan, Jr. 13760 in the United States of America, Endicott, NY, Monroe Street 1900 (72) Inventor James Ralph Petrozero United States of America 13760, Endicott, NY, Hill Avenue 925 (56) References JP-A-4-341772 (JP, A) JP-A-4-262373 (JP, A) JP-A-1-89487 (JP, U) JP-A-1-64863 (JP) , U)

Claims (10)

(57) [Claims] An electric conductor on a first electric circuit member is connected to a second electric circuit member.
An interconnect that is electrically interconnected to an electrical conductor on an electrical circuit member of claim 1, wherein the insulating sheet is adapted to be disposed between the first and second electrical circuit members, wherein one side has 0.875m
m and a plurality of rectangular windows 91 arranged in rows and columns, and electrically conductive elements arranged in each of the windows of the insulating sheet, each being within the window and being flush with each other. A relatively flat base portion and a resilient helical portion extending away from the flat base portion and the insulating sheet to connect an electrical conductor on one of the electrical circuit members in a non-wiping manner. An electrically conductive element, and an interconnect comprising: 2. The method according to claim 1, further comprising a plurality of dendritic elements disposed on said helical portion and connected to said electrical conductor.
The described interconnector. 3. The method according to claim 2, wherein the dendritic elements are palladium, platinum, rhodium, ruthenium, osmium, iridium,
3. The interconnect of claim 2, wherein the interconnect is comprised of a material selected from the group comprising: and tungsten. 4. The interconnect of claim 1 wherein said insulating sheet is comprised of polyimide. 5. The interconnect of claim 1, wherein said electrically conductive element is beryllium copper. 6. An interconnect according to claim 1, wherein said insulating sheet comprises first and second sheets sandwiching said base portion of said electrically conductive element from above and below. 7. The apparatus of claim 1, further comprising means disposed on said relatively flat base portion of said electrically conductive element for electrically contacting electrical conductors on said second electrical circuit member.
The described interconnector. 8. The second electrically conductive element extends from the base portion in a direction opposite to the first helical portion, the second helical portion being connected to the second helical portion.
2. The interconnect of claim 1 including a second resilient helical portion connecting the electrical conductors of the electrical circuit members of the first and second electrical circuits. 9. The first helical portion extends from the base portion in the same direction as the first helical portion.
2. The interconnect of claim 1 including a second resilient helical portion that provides double contact with the conductor of the electrical circuit member with the helical portion of the electrical circuit member. 10. A first electrical circuit member including at least one electrical conductor, a second electrical circuit member including at least one electrical conductor, and the electrical conductor on the first electrical circuit member, An electrical interconnect that electrically interconnects with the electrical conductor on the second electrical circuit member, the electrical assembly comprising:
An insulation sheet adapted to be disposed between the first and second electrical circuit members, the side being 0.875 m
m, a plurality of rectangular windows 91 having a width of not more than m, a relatively flat base portion disposed in or on the insulating sheet, and a direction away from the flat base portion and the insulating sheet. An elastic helical portion extending to connect an electrical conductor on one of the electrical circuit members in a non-wiping manner.